Type element support

ABSTRACT

Clearance take-up bias is added to the support structure for a rotatable type element to minimize variations in effective impact force previously induced by the existence of varied amounts of slippage and parts flexure that wasted a portion of the available impact energy.

[45] Nov. 13, 1973 United States-Patent Miles et al.

PATENTE IUY l 3 |913 FIG. 2

INVENToRs GEORGE T. MILES sELAHAmN A. oKcuocLu BY @w ATTORN Y TYPE ELEMENT SUPPORT BACKGROUND The typewriter described in U. S. Pat. No. 2,919,002

employs a spherical type element carrying a number of characters spaced at regular intervals about its surface. To type individual characters the type element is rotated and tilted by variable amounts from a home position. The entire type element is then driven against an ink ribbon to print the character. It can be appreciated that lightweight parts of simple construction are essential to high speed typing operations.

The rotational support for the type element is normally made of simple sliding type bearings that include some small radial clearance as a virtual necessity. Unfortunately, this radial clearance may allow lateral shifting of the type element during impact as the clearance is taken up by the force of impact.

The type element is preferably made of a light weight material to minimize inertia. Flexure of the type element material is minimized by an anvil that supports the portion of the type element being impacted. The anvil cannot, however, be effective until contacted by the type element and radial clearance in the type element support can allow the type element to be spaced from the anvil.

It has been discovered that the effective impact force of the type element varies significantly between typing operations. Thus, to achieve uniformly dense characters, it is necessary to increase the average impact force to insure adequate force under worst case conditions. The ability to increase average force, however, is limited by the ability of ribbons to withstand cutting and the necessity to avoid penetration of the typing paper by small characters. lt can be appreciated that a highly variable or unpredictable impact force, therefore, can limit the choice of usable supplies such as ink ribbons and papers and also can limit choice of usable type styles.

DISCLOSURE OF THE INVENTION We have found that the variability of impact force is caused, to a great extent, by effective energy losses resulting from the presence of clearance in the type element support described above.

The energy expended in laterally shifting the type element on its support, and the energy absorbed in flexing the type element prior to its contact with the anvil, is not available to generate impact force. Accordingly, the ultimate impact force developed is a function ofthe clearance that is taken up during impact prior to development of a good supporting engagement of the anvil with the type element. The amount of clearance available to be taken up at any given impact will vary depending upon the particular sequence of characters typed and their location relative to the type element. If, for example, characters are selected in sequence from opposite hemispheres of the type element, impact from the first character will place all clearance in the support in location to be taken up upon impact of the subsequent character. Conversely, after impact of a given character and the takeup of clearance associated therewith, the same character can be repeated with no further clearance takeup to rob impact energy. It can be seen that random selection of characters from various angular positions on the type element will produce random amounts of clearance to subtract random amounts of energy from thetype element impact and thus contribute to a lack of impact force predictability.

Our invention provides a biasing spring that urges the rotational supporting parts for the type element in a direction to continuously take up all lateral clearance and maintain the type element in contact with the anvil at all times. Accordingly, impact of any character selected cannot displace the type element relative to the anvil, to detract from the impact energy. The impact force thus becomes substantially more predictable. Several benefits result. It is possible to lower the maximum impact force designed into a given system since a large safety factor is not required to accomodate the unpredictability. Wear and noise associated with high impact force can be reduced. It is possible to acommodate type character shapes that are more demanding of predictable or controlled impact force such as those having broad area portions or those having fairly sharp fine lines. Also it is possible to accommodate a wider variety of supplies such as ink ribbons which maybe rather intolerant to either low or high force extremes. All in all, the finesse of a more predictable impact force contributes to a higher reliability of machine operation.

ln addition to impact predictability, it has been observed that a noise increment can be generated by resonance of the type element. This increment of noise is reduced by our invention through the clamping action of the anvil which is continually in contact with the type element. v

These and other objects, features and advantages of our invention will be apparent to those skilled in the art from the following description of a specific illustrative embodiment of our inventive concepts wherein reference is made to the accompanying drawing of which:

FIG. l shows a vertical cross-sectional view of a type element support portion of a printer constructed in accordance with our invention as the parts would be positioned at the point of impact, and

FIG. 2 is a cross-sectional plan view of the type element support shown in FIG. l and taken along lines Il II thereof.

More specifically, FIG. l shows a typewriter or printer l0 that can be of the construction generally disclosed in U. S. Pat. No. 2,919,002. The typewriter includes a truncated spherical type element 20 having four concentric rows of character masters 2l on its external surface for selective positioning to an impact point 22 relative to a paper support platen l l. The type element 20 is removeably received by its mounting bore part 23 by a mounting post portion 30 of a rotating axle 31. A spring clip 24 that may be of the design shown in U. S. Pat. No. 3,307,677 removably retains the type element 20 on the post 30. A key pin 32 that is embedded in the post 30 engages a cutout groove 25 in the type element 20 to connect the type element 20 to the post 30 for unitary rotation.

The axle 3l is rotatably received by a support member or tilt ring 40 that is pivoted on a vertical support standard 50 by axle pins 5l. The standard 50 is mounted on a rocker member 52 that is pivoted to a letter feed carrier 12 for allowing impact movement of the type element 20 by hollow shaft 13.

Normally the type element 20 is pivoted by spring 14 back from its position as shown to the broken line position indicated. When impact is desired, a print cam 15 is rotated to drive cam follower 16 counter-clockwise to its full line position as shown. The type element 20 thus, is pivotedly thrown by transfer pin 53 and rocker 52, to its position as shown, to produce impact with the platen 11.

As shown more completely in U. S. Pat. No. 2,926,768 the axle 31 is rotatably driven by a pulley 54 that is connected thereto through a vertical shaft 55 and an articulated joint 56 thereby enabling the selection of different characters 21 by rotation of the type element 20. As mentioned above, axle 31 is rotatably supported in tilt ring 40. This support is provided by a bearing bore 41 in the tilt ring 40 that is slightly larger than a axle bearing portion 33 concentric therewith. The difference in size of the bore 41 and the bearing portion 33 provides clearance 42 that is somewhat exaggerated in the drawings. While this clearance can be minimized, it cannot as a practical matter be eliminated. The tilt ring 40 also includes an anvil portion 43 that is positioned adjacent to the line of impact force to provide support for the type element during impact. Retaining plate 44 and a pair of spacer shims 45 are fixed to the tilt ring 40 by screws 46 and entrap an axle flange part 34 with a running fit.

For reasons of practical manufacture, some clearance 35 also exists between the mounting bore 23 of the type element and the mounting post 30 of the axle 31. The clearance 3S and clearance 42, if uncontrolled, would cause variation in the ultimate impact force as in the case of the prior art device. In our mechanism, the adverse effects of these clearances, however are effectively taken out of the system by the continuous urging by a two arm leaf spring 60 that drives the axle 3l leftwardly and the type element 20 leftwardly as far as necessary to maintain the internal surface 26 of the type element 20 against the anvil 43.

As best seen in FIG. 2, the tilt ring 40 has a cavity portion 47 located between the anvil 43 and the axle 3l. The leaf spring 60 is trapped in the cavity 47 to bias the axle 31 and the type element 20 leftwardly thereby maintaining the type element 20 in continuous supported engagement with the anvil 43. The two arm spring 60 has a first arm 61 that slideably engages the bearing portion 33 of axle 3l and a second arm 62 that is curved to closely engage the wall of cavity 47 and thereby provide a well supported, stable configuration.

In operation, the impact energy from cam 15 will be uniformly available for print of any character since the energy wasting clearances 35 and 42 are continuously taken up by the action of spring 60.

While a specific preferred illustrative embodiment of our inventive concept has been shown herein, it will be recognized by those skilled in the art that various modications, deletions and additions can be made without departing from the spirit and useful benefits of our invention. Accordingly, the scope of our inventive concept is to be limited only by the appended claims.

We claim:

l. A printer having a type element including a mounting part and a platen, means mounting said type element and said platen for relative movement into mutual impact cooperation to define a printing point therebetween, a support member having a bearing bore, axle means including a first bearing portion that is slightly smaller than said bearing bore, and a post for loosely receiving said type element mounting part, said axle means bearing portion being rotatably carried by said support member bearing bore, means for rotating said axle means to different angular positions, means connecting said type element to said axle means for rotation therewith, and an anvil supportedly mounted on said support member and positioned internally of said type element adjacent said printing point for supporting said type element against impact induced displacements, wherein the improvement comprises:

urging means carried by said support member internally of said type element and operatively interposed between said type element and said support member for constantly urging said type element into contact with said anvil.

2. A printer as defined in claim 1 wherein said urging means comprises a spring urged engaging part that slidably engages said axle means.

3. A printer as defined in claim l wherein said urging means comprises a folded spring including a pair of spring arms, with one of said spring arms engaging said support member and the other of said spring arms slideably engaging said axle means.

4. A printer having a type element including a mounting part and a platen, means mounting said type element and said platen for relative movement into mutual impact cooperation to define a printing point therebetween, a support member having a bearing bore, axle means including a first bearing portion that is slightly smaller than said bearing bore, and a post for loosely receiving said type element mounting part, said axle means bearing portion being rotatable carried by said support member bearing bore, means for rotating said axle means to different angular positions, means connecting said type element to said axle means for rotation therewith, and an anvil supportedly mounted on said support member and positioned internally of said type element adjacent said printing point for supporting said type element against impact induced displacements, wherein the improvement comprises:

a cavity portion formed in said support member and located adjacent said support member bearing bore and between said support member bearing bore and said anvil, and

urging means comprising a folded spring including a pair of spring arms located in said cavity portion with one of said spring arms engaging said support member and the other of said spring arms slidably engaging said axle means.

5. A printer as defined in claim 4 wherein the exterior surface of said type element is of the general configuration of a truncated sphere.

6. A printer as defined in claim 4 further comprising pivot means movably mounting said support member on a further support for movement to different angular positions.

7. A printer as defined in claim 4 further including means removably retaining said type element upon said axle means. 

1. A printer having a type element including a mounting part and a platen, means mounting said type element and said platen for relative movement into mutual impact cooperation to define a printing point therebetween, a support member having a bearing bore, axle means including a first bearing portion that is slightly smaller than said bearing bore, and a post for loosely receiving said type element mounting part, said axle means bearing portion being rotatably carried by said support member bearing bore, means for rotating said axle means to different angular positions, means connecting said type element to said axle means for rotation therewith, and an anvil supportedly mounted on said support member and positioned internally of said type element adjacent said printing point for supporting said type element against impact induced displacements, wherein the improvement comprises: urging means carried by said support member internally of said type element and operatively interposed between said type element and said support member for constantly urging said type element into contact with said anvil.
 2. A printer as defined in claim 1 wherein said urging means comprises a spring urged engaging part that slidAbly engages said axle means.
 3. A printer as defined in claim 1 wherein said urging means comprises a folded spring including a pair of spring arms, with one of said spring arms engaging said support member and the other of said spring arms slideably engaging said axle means.
 4. A printer having a type element including a mounting part and a platen, means mounting said type element and said platen for relative movement into mutual impact cooperation to define a printing point therebetween, a support member having a bearing bore, axle means including a first bearing portion that is slightly smaller than said bearing bore, and a post for loosely receiving said type element mounting part, said axle means bearing portion being rotatable carried by said support member bearing bore, means for rotating said axle means to different angular positions, means connecting said type element to said axle means for rotation therewith, and an anvil supportedly mounted on said support member and positioned internally of said type element adjacent said printing point for supporting said type element against impact induced displacements, wherein the improvement comprises: a cavity portion formed in said support member and located adjacent said support member bearing bore and between said support member bearing bore and said anvil, and urging means comprising a folded spring including a pair of spring arms located in said cavity portion with one of said spring arms engaging said support member and the other of said spring arms slidably engaging said axle means.
 5. A printer as defined in claim 4 wherein the exterior surface of said type element is of the general configuration of a truncated sphere.
 6. A printer as defined in claim 4 further comprising pivot means movably mounting said support member on a further support for movement to different angular positions.
 7. A printer as defined in claim 4 further including means removably retaining said type element upon said axle means. 